messaging-java

Message Queue Integration Library for Java

Supported Message Brokers

• RabbitMQ
• JMS based Message Brokers

Using the library

Setup

In order to use the library, include the following in the pom.xml of your project:

<dependencies>
	<dependency>
		<groupId>com.github.libgraviton</groupId>
		<artifactId>messaging</artifactId>
		<version>LATEST</version>
	</dependency>
</dependencies>

Make sure that version points to the newest release on maven central (see badge above).

Publish Messages

To publish messages you need an instance of QueueConnection, which represents the connection to the Message Queue. Once you have a QueueConnection, you can simply do the following to publish a message:

QueueConnection connection = new RabbitMqConnection.Builder().queueName("your-queue").build();

try {
    connection.publish("the message");
} catch (CannotPublishMessage e) {
    // Message publishment failed for some reason.
    fail(String.format("An exception occurred: '%s'", e.getClass().getName()));
}

Consume Messages

To consume messages you need an instance of QueueConnection, which represents the connection to the Message Queue.

Once you have a QueueConnection, you can simply do the following to consume a message:

Consumer consumer = new Consumer() {

    @Override
    public void consume(String messageId, String message) throws CannotConsumeMessage {
        System.out.println(String.format("Received message with id '%s': '%s'", messageId, message));
    }

};

QueueConnection connection = new RabbitMqConnection.Builder().queueName("your-queue").build();

try {
    connection.consume(consumer);
} catch (CannotRegisterConsumer e) {
    // Consumer registration failed for some reason.
    fail(String.format("An exception occurred: '%s'", e.getClass().getName()));
}

In this case, each message gets automatically acknowledged. If you want to handle message acknowledgment yourself, you need to register an AcknowledgingConsumer:

Consumer consumer = new AcknowledgingConsumer() {

    private MessageAcknowledger acknowledger;

    @Override
    public void setAcknowledger(MessageAcknowledger acknowledger) {
        this.acknowledger = acknowledger;
    }

    @Override
    public void consume(String messageId, String message) throws CannotConsumeMessage {
        System.out.println(String.format("Received message with id '%s': '%s'", messageId, message));
        try {
            acknowledger.acknowledge(messageId);
        } catch (CannotAcknowledgeMessage e) {
            // Message Acknowledgment failed for some reason
            throw new CannotConsumeMessage(messageId, message, e);
        }
    }

};

QueueConnection connection = new RabbitMqConnection.Builder().queueName("your-queue").build();

try {
    connection.consume(consumer);
} catch (CannotRegisterConsumer e) {
    // Consumer registration failed for some reason.
    fail(String.format("An exception occurred: '%s'", e.getClass().getName()));
}